Also on the subject of the tape, I have to tell you that Brenda did not sound frantic as is being portrayed in all the news stories. And I have something to use for comparison--other 911 calls made by mothers who've found their children gone. We do hear them fairly frequently.
And then there are the faked distress calls--we now know they were faked because later it comes out that the person calling either knew what had happened, or had done it herself, like Susan Smith.
We had a local case that is a perfect example: the woman called 911 reporting a "home invasion" where a "masked man" shot her in the hand and fatally wounded her husband. She did the same "Oh my God" in a flat voice as Brenda. Now, it comes out that she and one of her (many) lovers murdered her husband (why can't people just get a divorce?) and she and the lover (who fled to Mexico just before hubby's funeral) are standing trial for it.
Now, please note before flaming that these are my impressions of Brenda's "frantic" 911 call, and should not in any way be construed as fact unless and until evidence proves me right. (And it wouldn't surprise me in the least if it did.)